I'm having a problem with my bike, and need some help quickly. Three friends, and I are going to Death Valley on Wed the 19. My bike pretty much refuse's to start. It turns over slowly, and drains the new battery quickly. The auto decomp bangs like crazy while the starter is engaged, but will not fire. We thought to change the small spring in the auto decomp, and I cleaned the carb at the same time. The bike turns a bit better, but still refuses to start. I got it started once today, and it ran real nice. But refused to start again. When it did start, I had the manual decomp pulled in, and it spun real fast and finally started. We had it running for about five minutes, shut it off, and could not start it again. We also had a car battery hooked up to my bike battery. The bike has 28,000 kilometers on it (17,000 miles), and has had the valves adjusted. Thanks Gary
Goat, Check your connections at the battery for breakage , especially the ground(-) connection. Is the car battery known to be good? Let's have some volt meter readings for the battery. Maybe your 'new' battery is shot. If not it's the starter, easy to remove. Take it to a shop and have them test it/fix it. Or try yourself. bill
The car battery never stopped the bike from turning, the bike battery would just get weak. The battery is a Oddesy 310, and has been on a trickle since new last summer. The 640 turns, but will not fire. I'll try the kick, but man, its like pushing a bus down the road with one leg.
Hey Guys, I've been the poor sap wrenching on GG's 640A. I'll give you some background: Bike will not kick start. Seriously, I have an XR650R that I find extremely easy to kick. I'm on the north side of 200 lbs and have no hope of kicking the 640A. Zero All cabling to the starter has been checked, removed, cleaned and tightened. The car battery came out of my Mustang and had zero problems starting it. I left it overnight on the charger to be sure When you hold the decomp in, it turns over fast and quiet. As soon as you let it out and the auto decomp takes over, the starter has problems turing the motor over more than a few time before it stops. This is when it sounds like someone dropped a bag of wrenches into the motor. We just had the top end apart and replaced the auto decompressor spring. This resulted in slightly better turnover performance. Prior to changing the spring the motor would not turn over at all with the starter. I could put my entire weight on the kick and it would only slowly move. My thoughts: Although I havent looked at it yet, I'm wondering if the bearing/bushing that supports the starter gear is worn out. This could explain a weak starter as well as the horible noises. Thoughts? Thanks guys, Wes
Actually, it doesnt turn more than a few times. Once, with both batteries extremely fresh and the starter and cabling nice and cool it did start and ran fantastically. The lack of turning is the problem.
OK, does the plug have a good spark? I ran my bike for close to a year with a worn out decomp and used the manual lever for starter assist with no problems.... Just hold it in to get the engine spinning and let it out, with a good battery and spark it should fire up.... Is their any noise coming from the starter clutch in the right side case when you spin the motor, when it slips it make a hell of a racket... It could also happen the this clutch isn't releasing and still dragging the starter motor around... Does the autodecomp cam rattle at all speeds or just below 1700 rpm? Nico was onto the valves, are the clearances set properly? Are the cam follower rollers OK? Because if the valves are not opening fully the engine will be hard to turn over.. Also did you get the cam sprocket, camshaft marks lined up properly when you reinstalled the cam? With the engine locked at TDC the marks must line up as shown on this page:http://www.advrider.com/forums/showthread.php?t=632893&page=8 One other thing to check is the piston crown/ cylinder for excessive carbon build up, this will raise your compression and make the engine harder to turn over... You can get a partial idea by shining a flashlight down the spark plug hole, but to properly inspect the head should come off... At the same time your looking through the plug hole try to inspect the edge of the piston above the ring lands for broken edges... This is where fiber optics would come in real handy.... One other thing that could cause problems is a worn float needle /seat in the carb that allows too much fuel into the cylinder causing a compression lock of sorts... If the float needle has never been replaced in 28,000 km life of the bike then it is likely due... Also while we're on the carb subject, also check the jet needle in the slide assembly for wear and the corresponding needle jet for oval wear... Good luck....
We hear a "hell of a racket" only when the E button is engaged, not when the bike is running. It sounds like a pop can in a dryer. I don't remember hearing that racket before the non starting problem began. Like Wes said, the bike turns a few time, and abruptly stops. There is no banging when the manual decomp is engaged, and that is how it started the one time for us.
Carb is minty fresh, engine runs and responds like a new motor (when it actually starts). Zero carb issues Valvetrain is minty fresh and properly adjusted I cant imagine the volume of carbon buildup that would significantly effect compression ratio. Considering how nice the internals and plug look this is very unlikely. Regardless, a functioning auto decompressor would make this a moot point. So, back to the starter. All points indicate that the starter clutch is slipping which would make sense considering how incredibly difficult the motor is to turn over. That being said, I dont believe this is the cause of the poor starting but a result of the motor being too difficult to turn over, ie the auto decomp not working. But, I have been wrong before, and I will be again, so I'll chase the starter clutch problem, which sounds like its very likely an issue. GG has been starting the bike by pulling in the decomp lever, spinning the motor, then releasing the decomp since the day he bought it. It has worked but has been getting steadily worse over the last year or so. That being said, the bike had seen very little use so I guess it has degraded fairly rapidly. Heck, if you try to push start this thing it'll lock up the motor in 5th gear and I know how to push start a bike. A 200 lb guy jumping and dumping the clutch right as I land on the seat and it still just locks up. It really does sound like someone dropped a bag or wrenches in the motor when the starter is working... Wesley J
Sounds like the sprague clutch may be slipping. The de-comp should be working, so long as it is back together properly. You guys said you replaced the spring, right? Pull the manual lever and see if it makes a difference. Just a note, .008"=.20mm. That is .05mm out of spec, too loose. Would lead to valves staying closed too long and bumping compression up a bit, no? Probably not the root of the problem, but something you should adjust. Unless of course, '03 was an odd year and KTM decided they needed sloppier valves.
Both exhaust and intake valves should be set at .006" or 0.15 mm.... It sounds like his auto decomp has never worked so a new cam is likely the only fix for that issue... You can test the function of the auto decomp with the engine running: Turn the idle down below 1500 and if it clatters before the stall point it works and if none is heard then it is toast... And with the auto decomp not functioning for a long time it is likely that the extra strain will have damaged the starter sprague clutch... Also a poor battery may do the same as it does not drive the sprague out with enough force to grab the drum and will slip and wear the surface... By saying the carb is minty fresh you mean there is no wear on the internal parts? Does the bike need to be choked to start when you manage to get it going? And is the battery fresh or do you just charge it or jump it off the big battery? I will mention that if your battery is in poor condition these bikes will experience difficult starting as the starter robs power from the ignition... If you are in doubt have the battery load tested...
I never heard the banging and clanging until recently even with the bike running. The bike was always slow to turn, hence the new Oddessy 310 battery last year. The E start drains the battery quickly after a few try's of turning. I bought the bike two years ago, and have alway used the manual decomp to aid the E start as demonstrated by PO. Get the starter spinning quickly and release manual decomp.
I removed the carb, and gave it a good cleaning, as per "BST bible thread" Thank you Laramie LC4. I could see no wear on any parts, and the only change was to drill the slide as specked in the BST bible. When the bike started for the brief 5 minutes, it was super responsive to the throttle. When the cam was removed, it didn't look to have any wear. Is a worn cam not visual? It sure sounds expensive if both the cam/decomp, and sprague need to be replaced.
Gunnerbuck thanks, you sent me on a chase, and I found this thread. http://www.advrider.com/forums/showthread.php?t=222515 Sounds like it could be the same noise. If the worn sprague clutch let out some little bits, that could stop the starter from spinning?
The intake and exhaust cam lobes may be in perfect condition while the decomp cam, being a moving part could be totally shot... What wears on the decomp system is the camshaft pin that engages it or the recess slot on the decomp cam itself... It is possible that something is dragging in the starter clutch assembly... Good Luck...
It has to be something in the starting mechanism. It cant be the auto decomp. As someone stated earlier it is easily bypassed by use of the manual release. The battery is not it from thier use of the car battery. Its not the valves. Although lose valves do cause a starting problem. It is a "will not start" issue not a cant "turn over" issue. It's not the carb because it runs fine once running. And agian we are dealing with resistance to turning over issue. Which would is not a carb problem. To me you have all pretty much isolated it to the starter. As many have suggested. My guess is that the starter is drive is stuck in the out position and is always engaged with the engine. Thus turning the whole time the motor is running. Which in turn has damaged something to the point of siezure. Most likely a bearing. Probally in the starter. that's guess anyway. Good luck Oh yeah on a side note. A good way to test for auto decomp wear is to slowly kick it over. You should hear a very hard knock from the decomp lever clearing the pin in the cam. If it's a light tick it means your pin in the cam is getting worn. If you hear nothing it's toast. Its best to remove the silencer to really hear it well.
